The clinical relevance of microsatellite alterations in head and neck squamous cell carcinoma: a critical review

Extracellular Vesicles for Childhood Cancer Liquid Biopsy

Liquid biopsy involves the utilization of minimally invasive or noninvasive techniques to detect biomarkers in biofluids for disease diagnosis, monitoring, or guiding treatments. This approach is promising for the early diagnosis of childhood cancer, especially for brain tumors, where tissue biopsies are more challenging and cause late detection. Extracellular vesicles offer several characteristics that make them ideal resources for childhood cancer liquid biopsy. Extracellular vesicles are nanosized particles, primarily secreted by all cell types into body fluids such as blood and urine, and contain molecular cargos, i.e., lipids, proteins, and nucleic acids of original cells. Notably, the lipid bilayer-enclosed structure of extracellular vesicles protects their cargos from enzymatic degradation in the extracellular milieu. Proteins and nucleic acids of extracellular vesicles represent genetic alterations and molecular profiles of childhood cancer, thus serving as promising resources for precision medicine in cancer diagnosis, treatment monitoring, and prognosis prediction. This review evaluates the recent progress of extracellular vesicles as a liquid biopsy platform for various types of childhood cancer, discusses the mechanistic roles of molecular cargos in carcinogenesis and metastasis, and provides perspectives on extracellular vesicle-guided therapeutic intervention. Extracellular vesicle-based liquid biopsy for childhood cancer may ultimately contribute to improving patient outcomes.

Immuno-Oncological Biomarkers for Squamous Cell Cancer of the Head and Neck: Current State of the Art and Future Perspectives

The era of immune checkpoint inhibitors has altered the therapeutic landscape in squamous cell cancer of the head and neck (SCCHN). Our knowledge about the tumor microenvironment has fueled the research in SCCHN, leading to several well-known and less-known prognostic and predictive biomarkers. The clinical staging, p16/HPV status, and PD-L1 expression are currently the main tools for assessing the patients' diagnosis and prognosis. However, several novel biomarkers have been thoroughly investigated, some reaching actual significant clinical contributions. The untangling of the immune infiltrate with the subtyping of tissue-associated tumor infiltrating lymphocytes, tumor-associated macrophages, and circulating blood-based biomarkers are an interesting avenue to be further explored and prospectively assessed. Although PD-L1 expression remains the most important response predictor for immune checkpoint inhibitors, several flaws impede proper assessment such as technical issues, different scoring protocol, and intra-, inter-, and temporal heterogeneity. In addition, the construction of an immune-related gene panel has been proposed as a prognostic and predictive stratification but lacks consensus. Recently, the role of microbioma have also been explored regarding its systemic and antitumor immunity. This review gives a comprehensive overview of the aforementioned topics in SCCHN. To this end, the integration of these clinically advantageous biomarkers via construction of an immunogram or nomogram could be an invaluable tool for SCCHN in future prospects.

Predictive factors in the treatment of oral squamous cell carcinoma using PD-1/PD-L1 inhibitors

Due to immune impairment and lymphocyte enrichment of oral squamous cell carcinoma (OSCC), anti-PD-1/PD-L1 therapy is regarded as a potential treatment option. However, tumor heterogeneity, differences in the immune conditions of patients, and the interrelation between tumor cells and stromal cells within the tumor microenvironment (TME) could affect the therapeutic efficacy of immune checkpoint blockades. Therefore, to maximize the benefit of blockade PD-1/PD-L1 axis, to find an efficient predictor (the possible clinical parameters or biological factors) before treatment are of great importance. In this review, we discuss the advantages of anti-PD-1/PD-L1 therapy for OSCC patients and find three respects that are currently available in predicting curative effect. Firstly, OSCC with high PD-L1 expression evaluating by immunohistochemistry (high tumor proportion score (TPS) and combined positive score (CPS)) are considered to be suitable for anti-PD-1/PD-L1 therapy. Secondly, gene-level predictive biomarkers including high metastatic mismatch repair deficiency (dMMR) signature or enrichment of interferon-γ and PD1 signaling pathway is expected to be favorable factors. Besides, PET/CT parameters (SUV_max, MTV, TLG) are proved to be correlated with PD-L1 expression, and some newly developed immunoPET probes are enlarging the application of PET/CT in predicting therapeutic efficacy of PD-1/PD-L1 inhibitors.

The Mismatch Repair System (MMR) in Head and Neck Carcinogenesis and Its Role in Modulating the Response to Immunotherapy: A Critical Review

Simple Summary

The dysfunction of the mismatch repair system, an important mechanism for the detection and correction of DNA replication mistakes, may often lead to instability in the length of specific genetic sequences, known as microsatellites, and to the accumulation of mutations. Microsatellite instability is a well-known risk factor for the development of colorectal cancers and other types of tumors but is also considered a positive predictor of the immunotherapy response. Malignancies harboring such a specific genomic instability are very immunogenic because of the great number of aberrant antigens they produce. Therapies based on the blockade of specific immune checkpoints have shown to induce an effective immune response against microsatellite-unstable cancer. Many studies proved that microsatellite instability has a decisive role in the carcinogenesis and the malignant progression of head and neck cancer and, in the near future, it may become a useful tool in tailoring immunotherapy also in this field of precision oncology.

Abstract

The mismatch repair (MMR) system has a major role in the detection and correction of DNA replication errors, resulting from DNA polymerase slippage or nucleotides misincorporation. Specific inherited/acquired alterations or epigenetic inactivation of MMR genes are associated with microsatellite instability (MSI): the loss of crucial function in repairing DNA alterations can promote carcinogenesis by favoring the accumulation of thousands of mutations in a broad spectrum of different anatomic sites such as colon, stomach, prostate, esophagus, endometrium, lung and head and neck. Recent extensive data suggest that tumor mutational burden strongly correlates with a clinical response to immunotherapy using checkpoint inhibitors and this response is influenced by MMR deficiency in a wide range of human solid cancers. In this context, few data about this crucial point are available for head and neck cancer (HNC). In this review, we discuss the role of MMR alterations and the resulting MSI in HNC pathogenesis. Furthermore, by summarizing the clinical available data on how they influence the progression of precancerous lesions and the risk of recurrence or second primary tumors, we want to define the current role of MSI in the management of HNC. Finally, we analyze the complex interaction between cancer cells and the immune system addressing the data now available about a potential correlation between microsatellite instability and immunotherapy response in HNC.

Clinicopathological Significance of Overall Frequency of Allelic Loss (OFAL) in Lesions Derived from Thyroid Follicular Cell

Background

Loss of heterozygosity (LOH) and microsatellite instability (MSI) are frequent molecular events in thyroid tumor etiopathogenesis occurring in several chromosomal critical areas, including 3p12–25.3, 7q21–31, 10q22–24, and 15q11–13, with loci of tumor suppressor genes.

Objective

We evaluated the usefulness of LOH/MSI as a diagnostic/prognostic biomarker in lesions derived from thyroid follicular cells: follicular thyroid carcinoma (FTC); follicular adenoma (FA), papillary thyroid carcinoma (PTC), and nodular goiter (NG).

Methods

We performed allelotyping (GeneMapper Software v. 4.0.) of ten microsatellite markers linked to the 1p31.2, 3p21.3, 3p24.2, 9p21.3, 11p15.5, and 16q22.1 region on DNA from 93 primary thyroid lesions then evaluated the LOH/MSI frequency and overall frequency of allelic loss (OFAL).

Results

We found regions with significantly increased frequency of LOH/MSI for specific histotypes: the 3p24.2 region for FA and 1p31.2 for FTC. LOH/MSI in 3p21.3 was significantly elevated in PTC and FTC. LOH/MSI in 3p21.3 was increased for small size tumors (T1a + T1b), tumors with no regional lymph node involvement (N0 + Nx), American Joint Committee on Cancer (AJCC) stage I tumors, and tumor diameter (Td) < 10 mm; in 1p31.2 for T2–3, N1, stage II–IV, and Td 10–30 mm; in 11p15.5 for T2–3, N1, stage II–IV, and Td > 30 mm. OFAL values were significantly higher in younger patients (< 40 years), in men, in those with T2–3 stage tumors, in those with increased Td, and in FA and FTC compared with NG and PTC.

Conclusions

We confirmed the occurrence of LOH/MSI in 3p21.3 at an early stage of tumorigenesis and mapped 1p31.2 and 11p15.5 as characteristic for advanced-stage tumors. The results of our study may enable consideration of OFAL, defined as LOH/MSI coincidence in various chromosomal regions, as a tumor progression marker. OFAL values were significantly higher in follicular neoplasms (FA and FTC) than in PTC or NG; hence, increased OFAL values can be regarded as a characteristic feature of the follicular phenotype.

Oral squamous cell cancer in a patient with Lynch syndrome

For patients with Lynch Syndrome (LS) (formerly known as hereditary nonpolyposis colorectal cancer or HNPCC), inheritance of one of several mutated mismatch repair genes (MMR) results in an increased risk for a variety of malignancies including colon, rectal, endometrial, urinary tract, gastric, small bowel and others [1]. Confirmation of increased risk of particular malignancies for patients harboring an MMR germline mutation has typically been the result of population studies of families tracked for the development of the possible associated cancer. When cancer results from inheritance of a particular mutated MMR gene, the malignancy has a characteristic fingerprint referred to as microsatellite instability-high (MSI-H), which results from deficient expression of the inherited MMR gene product (dMMR). Therefore, if sporadic tumors of a particular tissue of origin are only rarely dMMR, identifying a tumor as dMMR in a known LS family member suggests that, in that particular family, inheritance of the mutated MMR gene does predispose to that malignancy. Here we describe a patient diagnosed with a germline mutation in the MMR gene MSH6 who developed an oral pharynx cancer. Oral pharynx cancers are not known to be associated with LS. By confirming that the tumor was not dMMR and not MSI-H, it was concluded that his oral pharynx cancer was sporadic, rather than LS-related, and other family members carrying the mutated MSH6 are unlikely to be at above-average risk for the development of oral cancers, as a result of the LS. In additional, he would not be eligible for the so-called FDA agnostic approved immunotherapy which is endorsed for dMMR or MSI-H tumors [2].

The Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of squamous cell carcinoma of the head and neck (HNSCC)

Head and neck cancers, including those of the lip and oral cavity, nasal cavity, paranasal sinuses, oropharynx, larynx and nasopharynx represent nearly 700,000 new cases and 380,000 deaths worldwide per annum, and account for over 10,000 annual deaths in the United States alone. Improvement in outcomes are needed for patients with recurrent and or metastatic squamous cell carcinoma of the head and neck (HNSCC). In 2016, the US Food and Drug Administration (FDA) granted the first immunotherapeutic approvals - the anti-PD-1 immune checkpoint inhibitors nivolumab and pembrolizumab - for the treatment of patients with recurrent squamous cell carcinoma of the head and neck (HNSCC) that is refractory to platinum-based regimens. The European Commission followed in 2017 with approval of nivolumab for treatment of the same patient population, and shortly thereafter with approval of pembrolizumab monotherapy for the treatment of recurrent or metastatic HNSCC in adults whose tumors express PD-L1 with a ≥ 50% tumor proportion score and have progressed on or after platinum-containing chemotherapy. Then in 2019, the FDA granted approval for PD-1 inhibition as first-line treatment for patients with metastatic or unresectable, recurrent HNSCC, approving pembrolizumab in combination with platinum and fluorouracil for all patients with HNSCC and pembrolizumab as a single agent for patients with HNSCC whose tumors express a PD-L1 combined positive score ≥ 1. These approvals marked the first new therapies for these patients since 2006, as well as the first immunotherapeutic approvals in this disease. In light of the introduction of these novel therapies for the treatment of patients with head and neck cancer, The Society for Immunotherapy of Cancer (SITC) formed an expert committee tasked with generating consensus recommendations for emerging immunotherapies, including appropriate patient selection, therapy sequence, response monitoring, adverse event management, and biomarker testing. These consensus guidelines serve as a foundation to assist clinicians' understanding of the role of immunotherapies in this disease setting, and to standardize utilization across the field for patient benefit. Due to country-specific variances in approvals, availability and regulations regarding the discussed agents, this panel focused solely on FDA-approved drugs for the treatment of patients in the U.S.

Genetic analysis of surgical margins in oral cavity cancer

BACKGROUND

A histological, tumour-free surgical margin does not guarantee recurrence-free survival in patients with cancer. This study investigated the association between microsatellite alteration in tumour-free surgical margins and local recurrence in patients with oral cavity squamous cell carcinoma.

METHODS

Patients with histologically confirmed oral cavity squamous cell carcinoma were enrolled in this prospective study. Cancerous specimens, corresponding surgical margins and peripheral blood were obtained. Microsatellite alteration was investigated using six dinucleotide microsatellite markers. All samples were amplified by PCR, followed by automatic fragment analysis.

RESULTS

Microsatellite alteration was identified in 100 specimens (69·0 per cent) from 145 patients. Among them, 85 specimens carried loss of heterozygosity, whereas 55 had microsatellite instability (MSI). Patients with MSI at the surgical margin had a higher risk of local recurrence on multivariable analysis (odds ratio 7·17, 95 per cent c.i. 3·49 to 14·73).

CONCLUSION

Molecular assessment of surgical margins can help identify patients at risk of local recurrence.

Circulating tumor DNA as a biomarker and liquid biopsy in head and neck squamous cell carcinoma

The use of circulating biochemical molecular markers in head and neck cancer holds the promise of improved diagnostics, treatment planning, and posttreatment surveillance. In this review, we provide an introduction for the head and neck surgeon of the basic science, current evidence, and future applications of circulating tumor DNA (ctDNA) as a biomarker and liquid biopsy to detect tumor genetic heterogeneity in patients with head and neck squamous cell carcinoma (HNSCC).

Whole-exome sequencing identified mutational profiles of squamous cell carcinomas of anus

Anal squamous cell carcinoma (ASCC), either with human papillomavirus (+) or (-), is a neoplastic disease with frequent recurrence and metastasis. To characterize ASCC genomes, we attempted to disclose novel alterations of ASCC genomes and other genetic features including mutation signatures. We performed whole-exome sequencing and copy number alteration (CNA) profiling for 8 ASCC samples from 6 patients (2 cases with primary and recurrent/metastatic tumors). We found known ASCC mutations (TP53, CDKN2A, and PIK3CA) and CNAs (gains on 3q and 19q and losses on 11q and 13q). In addition, we discovered novel mutations in HRAS and ARID1A and CNAs (gain on 8q and losses 5q, 9p, 10q, and 19p) that had not been reported in ASCCs. We identified 4 signature patterns of the mutations (signatures 1 and 2 with deamination of 5-methyl-cytosin, signature 3 with APOBEC, and signature 4 with mismatch repair) in the ASCCs. Although signatures 1 to 3 have been detected in other SCCs, signature 4 was first identified in ASCCs. In addition, we first found that ASCCs harbored chromothripsis, copy-neutral losses of heterozygosity, and focal amplification of KLF5 super-enhancer. Analyses of primary and recurrent/metastatic pair genomes revealed that driver events in development and progression of ASCC might not be uniform. Our data indicate that ASCCs may have similar mutation and CNA profiles to other SCCs, but that there are unique genomic features of ASCCs as well. Our data may provide useful information for ASCC pathogenesis and for developing clinical strategies for ASCC.

Impact of microsatellite alteration in surgical margins on local recurrence in oral cavity cancer patients

The aim of this study was to investigate the association between microsatellite alteration in the surgical margins and local recurrence of oral cavity squamous cell carcinoma patients. Surgical specimens confirmed by pathological examination and corresponding surgical margins were collected from 120 oral cavity squamous cell carcinoma patients. Ten microsatellite markers were examined in the tumor specimens and paired surgical margins, which proved to be negative on pathological assessment. The specimens and surgical margins were amplified by polymerase chain reaction followed by computerized analysis. Forty-two specimens (35.0 %) with microsatellite instability (MSI) in at least one marker were found, and more than half of the specimens (n = 73, 60.8 %) had loss of heterozygosity (LOH) in at least one marker. Although MSI and LOH were not associated with the prognosis of oral cavity squamous cell carcinoma patients, presence of MSI in the tumor-free surgical margins increased the risk of local recurrence (hazard ratio: 9.549; 95 % confidence interval: 4.143-22.01). Genetic analysis of tumor-free surgical margins is a useful tool for identifying oral cavity squamous cell carcinoma patients who are vulnerable to local recurrence.

Microsatellite alteration in head and neck squamous cell carcinoma patients from a betel quid-prevalent region

We investigated the frequency of microsatellite alteration and their impact on survival in head and neck squamous cell carcinoma patients from an endemic betel quid chewing area. We collected 116 head and neck squamous cell carcinoma specimens along with corresponding surgical margins which were confirmed by pathological examination. Ten oligonucleotide markers were chosen for the assessment of microsatellite alteration. The specimens were amplified by polymerase chain reaction followed by automatic fragment analysis. There were 44 specimens (37.9%) with microsatellite instability (MSI) in at least one marker while more than half of the specimens (n = 68, 58.6%) had loss of heterozygosity (LOH) in at least one marker. Though MSI/LOH was not correlated with the survival of head and neck squamous cell carcinoma patients, presence of MSI in the tumor-free surgical margins was associated with local recurrence (odds ratio: 15.14; 95% confidence interval: 6.451 ~ 35.53; P < 0.001). Genomic assessment of surgical margin can help surgeons to identify head and neck squamous cell carcinoma patients who are at risk of developing local recurrence in a betel quid-prevalent region.

Molecular characterization of head and neck cancer: how close to personalized targeted therapy?

Molecular targeted therapy in head and neck squamous cell carcinoma (HNSCC) continues to make strides, and holds much promise. Cetuximab remains the sole US FDA-approved molecular targeted therapy available for HNSCC, though several new biologic agents targeting the epidermal growth factor receptor (EGFR) and other pathways are currently in the regulatory approval pipeline. While targeted therapies have the potential to be personalized, their current use in HNSCC is not personalized. This is illustrated for EGFR-targeted drugs, where EGFR as a molecular target has yet to be individualized for HNSCC. Future research needs to identify factors that correlate with response (or lack of one) and the underlying genotype-phenotype relationship that dictates this response. Comprehensive exploration of genetic and epigenetic landscapes in HNSCC is opening new frontiers to further enlighten and mechanistically inform newer as well as existing molecular targets, and to set a course for eventually translating these discoveries into therapies for patients. This opinion offers a snapshot of the evolution of molecular subtyping in HNSCC and its current clinical applicability, as well as new emergent paradigms with implications for controlling this disease in the future.

Epigenetic and genetic alterations-based molecular classification of head and neck cancer

The long-term survival rates for patients diagnosed with advanced head and neck cancer (HNC) remain poor. Many perplexing factors, including etiology and comorbidity, lead to different molecular malfunctions of HNC cells and determine the prognosis of the disease. Traditional diagnostic methods are limited in that they fail to provide an effective classification diagnosis, such as a more precise prediction of prognosis and decisions for personalized treatment regimens. Recently, molecular biology techniques, especially epigenetic and genetic techniques, have been developed that have enabled us to gain a greater insight into the molecular pathways underlying the cancers. Translating the research into a format that will facilitate effective molecular classification, support personalized treatment and determine prognosis remains a challenge. In this review, the authors provide an overview of cancer epigenetic and genetic alterations, tissue banks, and several promising biomarkers or candidates that may ultimately prove to be beneficial in a clinical setting for patients with HNC.

Malignant and nonmalignant gene signatures in squamous head and neck cancer

Genetic events specific to the pathogenesis of malignancy can offer clues to the tumorigenesis process. The objective of this study was to identify gene alterations that differentiate tumor and nontumor lesions in squamous head and neck cancer (HNSCC). DNA from 220 primary HNSCC with concurrently present tumor and nontumor lesions from the same patient was interrogated for genomic alterations of loss or gain of copy. Conditional logistic regression dealt with tumor and non-tumor records within a patient. Of 113 genes, 53 had univariate effects (P < 0.01), of which 16 genes remained in the multivariable model with P < 0.01. The model had a C-index (ROC) of 0.93. Loss of CDKN2B and gain of BCL6, FGF3, and PTP4A3 predicted tumor. Loss of BAK1 and CCND1 and gain of STCH predicted nontumor. This highly powered model assigned alterations in 16 genes specific for malignant versus nonmalignant lesions, supporting their contribution to the pathogenesis of HNSCC as well as their potential utility as relevant targets for further evaluation as markers of early detection and progression.

LOH-profiling by SNP-mapping in a case of multifocal head and neck cancer

AIM: To introduce an approach for the detection of putative genetic host factors that predispose patients to develop head and neck squamous cell carcinomas (HNSCC).

METHODS: HNSCC most often result from the accumulation of somatic gene alterations found in tumor cells. A cancer-predisposing genetic background must be expected in individuals who develop multiple cancers, starting at an unexpectedly young age or with little carcinogen exposure. Genome-wide loss of heterozygosity (LOH) profiling by single nucleotide polymorphism microarray mapping was performed in a patient with a remarkable history of multifocal HNSCC.

RESULTS: Regions of genomic deletions in germline DNA were identified on several chromosomes with a remarkable size between 1.6 Mb and 8.1 Mb (mega base-pair). No LOH was detected at the genomic location of the tumor suppressor gene P53.

CONCLUSION: Specific patterns of germline DNA deletions may be responsible for susceptibility to HNSCC and should be further analyzed.

[Analysis of microsatellite instability in laryngeal squamous cell carcinoma]

INTRODUCTION AND OBJECTIVES

The literature on the involvement of microsatellite instability in head and neck squamous cell carcinoma shows great variability, probably due to differences in the testing methods. Using a consensus detection system, we aimed to reach a reliable estimate of microsatellite instability prevalence in a subset of head and neck squamous cell carcinoma cases.

METHODS

The microsatellite instabilityI status of 43 patients with previously untreated primary laryngeal squamous cell carcinomas was analyzed by a multiplex polymerase chain reaction assay including 5 mononucleotide repeat markers.

RESULTS

Thirty-six cases showed a stable phenotype or a microsatellite stable phenotype (83.7%) and 7 cases (16.3%) showed an microsatellite instability-positive phenotype. One case showed instability in 3 of 5 markers, 1 case in 2 markers and 5 cases in 1 marker. The microsatellite instability-positive and stable cases did not differ with respect to age, tumour stage, lymph node or distant metastases.

CONCLUSIONS

Our data showed that a proportion of laryngeal squamous cell carcinomas are microsatellite instability positive. Knowledge of microsatellite instability patient status will allow adjusting anticancer therapy at an individual level.

[Analysis of microsatellite instability in laryngeal squamous cell carcinoma]

INTRODUCTION AND OBJECTIVES

The literature on the involvement of microsatellite instability in head and neck squamous cell carcinoma shows great variability, probably due to differences in the testing methods. Using a consensus detection system, we aimed to reach a reliable estimate of microsatellite instability prevalence in a subset of head and neck squamous cell carcinoma cases.

METHODS

The microsatellite instabilityI status of 43 patients with previously untreated primary laryngeal squamous cell carcinomas was analyzed by a multiplex polymerase chain reaction assay including 5 mononucleotide repeat markers.

RESULTS

Thirty-six cases showed a stable phenotype or a microsatellite stable phenotype (83.7%) and 7 cases (16.3%) showed an microsatellite instability-positive phenotype. One case showed instability in 3 of 5 markers, 1 case in 2 markers and 5 cases in 1 marker. The microsatellite instability-positive and stable cases did not differ with respect to age, tumour stage, lymph node or distant metastases.

CONCLUSIONS

Our data showed that a proportion of laryngeal squamous cell carcinomas are microsatellite instability positive. Knowledge of microsatellite instability patient status will allow adjusting anticancer therapy at an individual level.

Clinical significance of genome-wide minimally deleted regions in oral squamous cell carcinomas

Oral squamous cell carcinoma (OSCC) has the highest rate of increase among male cancers in Taiwan. An understanding of the molecular pathogenesis of this disease as well as the development of prognostic markers for the clinical management of this disease is very important. Thus, a systematic loss of heterozygosity (LOH) analysis was performed to define minimally deleted regions (MDRs) in 63 male OSCCs using 400 polymorphic microsatellite markers. For increasing reliability, genomic DNA was extracted from >90% tumor cells that had been purified by LCM, and only when a microsatellite marker provided LOH information in >30% of the OSCCs was there considered to be successful allelotyping. A correlation of the various MDRs with clinicopathological parameters and prognosis was carried out. In total, 32 MDRs were identified and ten were noted as novel. In addition, six MDRs were found to be associated with cigarette smoking. Among these markers, a loss of MDR c7r2 (7q32.2-q35) was significantly associated with poor disease-free survival (DFS) and ten MDRs were associated with allelic imbalance (AI) in tumors. Among the latter, a loss of MDR c14r1 (14q24.2-q32.12) and c11r1 (11q13.4-q25) had a synergistic effect on poor DFS and were able to reduce further the DFS rate in patients with MDR c7r2 loss. Taken together, the results generated in this study provide new insights that help with exploring the molecular mechanisms associated with OSCC tumorigenesis and cigarette smoking. They also should aid the development of potential prognostic markers for the clinical management of OSCC.

Multiple tumor-suppressor genes on chromosome 3p contribute to head and neck squamous cell carcinoma tumorigenesis

Head and neck squamous cell carcinoma (HNSCC) remains a significant cause of morbidity and mortality. There has been a great interest in finding specific genomic changes which contribute to HNSCC tumorigenesis, especially within the chromosome 3p area, where high frequency of LOH (loss of heterozygosity) has been reported. However, tumor-suppressor genes that may account for the frequent LOH remain to be identified. Recently, one systematic study of genomic sequencing was performed on breast and colorectal cancers and 189 candidate cancer genes (CAN-genes) were reported. Among those CAN-genes, 13 genes are located on chromosome 3p. To investigate whether any of the 13 CAN-genes on chromosome 3p is relevant to HNSCC tumorigenesis, we examined their mutational profiles in eight HNSCC cell lines and 12 tumor-normal pairs of human HNSCC in this study. Three of the 13 CAN-genes, ALS2CL, EPHA3, and CMYA1, each was found to harbor a missense mutation (1/20, 5% for each of the three genes). The mutations appeared hemizygous and SNP array analyses showed that these missense mutations are accompanied by LOH on the remaining allele. In summary, our data offer further support that ALS2CL, EPHA3, and CMYA1 are bona-fide tumor-suppressor genes and contribute to the tumorigenesis of HNSCC. Our data suggest that multiple tumor-suppressor genes are likely to be involved in accounting for the high LOH on chromosome 3p in HNSCC.

Prognostic utility of chromosomal instability detected by fluorescence in situ hybridization in fine-needle aspirates from oral squamous cell carcinomas

BACKGROUND

Although chromosomal instability (CIN) has been detected in many kinds of human malignancies by means of various methods, there is no practical assessment for small clinical specimens. In this study, we evaluated CIN in fine-needle aspiration (FNA) biopsied oral squamous cell carcinomas (SCCs) using fluorescence in situ hybridization (FISH) analysis, and investigated its prognostic significance.

METHODS

To evaluate CIN status of tumors, FISH with genomic probes for the centromeres of chromosomes 7, 9, and 11 was performed on specimens obtained by FNA from 77 patients with primary oral SCCs.

RESULTS

High-grade CIN (CIN3) was observed in 11.7% (9/77) of patients with oral SCCs and was associated significantly with reduced disease-free survival (p = .008) and overall survival (p = .003). Multivariate Cox proportional hazards analysis showed that CIN status was significantly correlated with disease-free survival (p = .035) and overall survival (p = .041).

CONCLUSION

Analysis of CIN status using FISH on FNA biopsy specimens may be useful in predicting of recurrence and poor prognosis in patients with oral SCCs.

Acquired somatic mutations in the microsatellite DNA, in children with bronchial asthma

OBJECTIVES

High incidence of genetic alterations at the microsatellite (MS) DNA level has been reported in asthmatic adults.

WORKING HYPOTHESIS

The aim of this study was to investigate whether microsatellite instability (MSI) and loss of heterozygosity (LOH) were detectable phenomena in children with asthma.

METHODOLOGY

DNA was extracted from sputum and blood cells of 27 children (10.8 +/- 2.5 years) with mild to moderate asthma, and from 8 healthy, never-smoked young adults. Fourteen polymorphic MS markers, namely D5S207, D5S820, D5S637, D6S344, D6S2223, D6S263, SGC35231, D11S1253, D11S1337, D11S97, USAT24G1, D13S273, D14S258, and D14S292, located on chromosomes (chr) 5q, 6p, 11q, 13q, and 14q were used to assess MSI and LOH.

RESULTS

None of the healthy subjects exhibited any genetic alteration. Five out of 27 children (18.5%) exhibited MSI or LOH in sputum cells versus blood samples from which 3 in the marker USAT24G1 (chr 13q14.1), 1 in the marker D14S258 (chr 14q23-q24.3), and 1 in the marker D5S637 (chr 5q12-q13). Compared to a previous study, with asthmatic adults, whereas MSI and/or LOH was exhibited in approximately 60% of the cases, the current study reported <20% of genetic alterations, at the MS DNA, in asthmatic children.

CONCLUSIONS

Our results showed that genetic instability in the MS DNA, is present in asthmatic children, but to less extent than in adult asthmatics from previous studies. These findings may support the hypothesis that somatic mutations may be early acquired in the natural course of asthma and could represent another contributor to the molecular pathogenesis of the disease. However, further studies are needed to clarify this hypothesis.

Clinical implications of microsatellite instability and MLH1 gene inactivation in sporadic insulinomas

CONTEXT

The molecular pathogenesis of sporadic insulinomas is unknown. There is a lack of biomarker to distinguish benign and malignant form of insulinoma.

OBJECTIVE

Our objective was to confirm the occurrence of microsatellite instability (MSI) in insulinomas, to identify alterations of mismatch repair (MMR) genes in the tumors, and to evaluate the possibility to distinguish benign and malignant insulinoma or to predict the clinical outcome of patients with these alterations.

DESIGN AND PATIENTS

We detected MSI and inactivation of MLH1 gene in 55 sporadic insulinomas by PCR, immunohistochemical staining, allelic typing, analysis of promoter methylation, and exon mutations. Their correlations with clinicopathological characteristics were analyzed with univariate and multivariate statistic analysis.

RESULTS

A high rate of MSI (MSI-H) was found in 33% of sporadic insulinomas. Reduced expression of mutL homolog 1 (MLH1) protein was observed in 36% of insulinomas and correlated with MSI-H (P = 0.008). Promoter methylation and loss of heterozygosity of MLH1 gene was found in 31 and 49% of insulinomas, respectively. Reduced expression of MLH1 and MSI-H were significantly associated with both tumor malignancy (P = 0.033 and P = 4.8 x 10(-6), respectively) and incurable disease (P = 0.006 and P = 0.001, respectively).

CONCLUSION

High frequency of MSI occurred in sporadic insulinomas. The silencing of MLH1 gene may partially contribute to the MSI-H in the tumors. Assessing MSI-H and expressions of MLH1 could be used to distinguish benign and malignant insulinomas and to predict the outcome of patients.

The prevalence of microsatellite instability in head and neck squamous cell carcinoma

PURPOSE

The present study aimed to use the most definitive available techniques to resolve controversy in the literature as to the prevalence of microsatellite instability (MSI) in head and neck squamous cell carcinoma (HNSCC).

METHODS

Eighty patients with advanced HNSCC were enrolled in the study that examined 20 microsatellite markers with automatic fragment analysis. These markers included ones derived from the NCI reference panel and ones previously reported to detect MSI in HNSCC (HNSCC panel).

RESULTS

Only one of 80 tumors could be considered positive for MSI. For this case, both panels showed MSI-High (8/10 positive markers for the NCI reference panel and 6/10 positive markers for the HNSCC panel). Qualitatively, the observed MSI could be classified as Type B MSI.

CONCLUSIONS

The present results indicate that MSI has a low prevalence in HNSCC.